Landscape genomics of a widely distributed snake (Dolichophis caspius, Gmelin, 1789) across Eastern Europe and Western Asia

Across the distribution of the Caspian whipsnake (Dolichophis caspius), populations have become increasingly disconnected due to habitat alterations. To understand population dynamics and the adaptive potential of this widespread but locally endangered snake, we investigated population structure, admixture and effective migration patterns. We took a landscape-genomic approach to identify selected genotypes associated with environmental variables relevant to D. caspius. With double-digest restriction-site associated DNA (ddRAD) sequencing of 53 samples resulting in 17,518 single nucleotide polymorphisms (SNPs), we identified eight clusters within D. caspius reflecting complex evolutionary patterns of the species. Estimated Effective Migration Surfaces (EEMS) revealed higher-than-average gene flow in most of the Balkan Peninsula and lower-than-average gene flow along the middle section of the Danube River. Landscape genomic analysis identified 751 selected genotypes correlated with seven ...